Parkinson Disease

Parkinson Disease is a topic covered in the Washington Manual of Medical Therapeutics.

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General Principles

  • Parkinson disease (PD) is a chronic, progressive neurodegenerative disease characterized by at least two of three cardinal features: resting tremor, bradykinesia, and rigidity. Often, postural instability is seen later in the disease.
  • The neurologic examination remains the gold standard diagnostic test for PD.
  • Cognitive dysfunction and dementia are common in PD (one-third of patients in most studies; six times higher than age-matched controls). Considerable overlap can occur between AD and PD.
    • One-third of PD patients are depressed.
    • Olfactory dysfunction, autonomic dysfunction, and sleep disorders are also common in PD and have a significant impact on quality of life.


Approximately 1 million people in the United States have been diagnosed with PD. Usually, the age at diagnosis is >50 years old. Approximately 1% of the population >50 years old has the disorder.

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